From 89c8277bbc5c20082e0eaff25c0ee7d6d3c89a48 Mon Sep 17 00:00:00 2001
From: "Claudius \"keldu\" Holeksa" <mail@keldu.de>
Date: Fri, 23 Jun 2023 08:09:41 +0200
Subject: c++, codec: Adding binary transport protocol

---
 src/codec/stream_value.h | 58 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)
 create mode 100644 src/codec/stream_value.h

(limited to 'src/codec/stream_value.h')

diff --git a/src/codec/stream_value.h b/src/codec/stream_value.h
new file mode 100644
index 0000000..df1334b
--- /dev/null
+++ b/src/codec/stream_value.h
@@ -0,0 +1,58 @@
+#pragma once
+
+#include "buffer.h"
+#include "error.h"
+
+#include <cstdint>
+#include <cstring>
+
+namespace saw {
+/**
+ * Helper class to encode/decode any primtive type into/from litte endian.
+ * The shift class does this by shifting bytes. This type of procedure is
+ * platform independent. So it does not matter if the memory layout is
+ * little endian or big endian
+ */
+template <typename T, size_t N> class ShiftStreamValue {
+public:
+	inline static error_or<void> decode(typename native_data_type<schema::Primitive<T,N>>::type &val, buffer &buff) {
+		if (buff.read_composite_length() < sizeof(T)) {
+			return make_error<err::buffer_exhausted>();
+		}
+
+		typename native_data_type<schema::Primitive<schema::UnsignedInteger,N>>::type raw = 0;
+
+		for (size_t i = 0; i < sizeof(T); ++i) {
+			raw |= (static_cast<uint64_t>(buff.read(i)) << (i * 8));
+		}
+
+		memcpy(&val, &raw, sizeof(T));
+		buff.read_advance(sizeof(T));
+
+		return void_t{};
+	}
+
+	inline static error_or<void> encode(const typename native_data_type<schema::Primitive<T,N>>::type &val, buffer &buff) {
+		error err = buff.write_require_length(sizeof(T));
+		if (err.failed()) {
+			return err;
+		}
+
+		typename native_data_type<schema::Primitive<schema::UnsignedInteger,N>>::type raw{};
+		memcpy(&raw, &val, sizeof(T));
+
+		for (size_t i = 0; i < sizeof(T); ++i) {
+			buffer.write(i) = raw >> (i * 8);
+		}
+
+		buffer.write_advance(sizeof(T));
+
+		return void_t{};
+	}
+
+	inline static size_t size() const { return N; }
+};
+
+template <typename T> using stream_value = shift_stream_value<T>;
+
+} // namespace saw
-- 
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